Transition fitting



Oct. 24, 1967 w. R. LEOPOLD, JR; ETAL 2 TRANSITION FITTING Original Filed Jan. 22, 1963 INVENTORS CA R L E. FLOR E ATTORNEYS United States Patent Ofiice 3,348,862 Patented Oct. 24, 1967 3,348,862 TRANSITION FIITIN G Wilbur R. Leopold, Jr., and Carl E. Floren, Decatur, 1ll., assignors to Mueller Co., Decatur, Ill., a corporation of Illinois Original application Jan. 22, 1963, Ser. No. 253,199, now Patent No. 3,245,701, dated Apr. 12, 1966. Divided and this application Sept. 16, 1965, Ser. No. 505,446

1 Claim. (Cl. 285-39) This invention has reference to a new and improved joint for connecting metal pipe such as steel to organic plastic pipe.

This application is a division of our copending application Ser. No. 253,199, filed Jan. 22, 1963, and now Patent No. 3,245,701.

Among the objects of the present invention are to provide: a new and improved transition joint for connecting the ends of metal and plastic pipes together; a transistion joint of the character described which utilizes a new and improved sealing arrangement between a metal coupler and a plastic adapter such that the threads which join the plastic adapter to the metal coupler do not have to be pressure tight, to keep the axial load off the resilient seal, e.g., an O-ring; a transition joint operative to keep exterior moisture from the seal.

Still further, the present invention contemplates the provision of a transition fitting of the character described which is of simple, reliable and trouble-free construction wherein the pipe is solvent welded or fusion welded to a plastic adapter, T, corporation stop, or the like. The adapter, in turn, is threadably engaged with a metal coupler which is welded to the end of the pipe. New and improved means for sealing the adjacent surfaces, of these elements is provided and the joint is characterized by a remarkable resistance to pressure and enhanced loading features as well as simplicity of assembly by unskilled workmen in the field.

These and still further objects, advantages, and novel features of the present invention will become apparent in the specification and claims taken in connection with the accompanying drawings.

In the drawings:

FIGURE 1 is a longitudinal section view of a transition joint according to the preferred embodiment of this invention;

FIGURE 2 is a sectional view taken along line 2-2 in FIGURE 1;

FIGURE 3' is an enlarged longitudinal section view of the sealing arrangement;

FIGURE 4 is a longitudinal section view with a modi fied embodiment of the transition joint, and

FIGURE 5 is a view taken along line 55 in FIG- URE 4.

Referring now to FIGURES 1-3, there is shown the end of a plastic pipe joined to the end 12 of a metal pipe such as steel, by a transition joint 14 according to the preferred embodiment of this invention.

The transition joint 14 includes a generally cylindrical plastic adapter 16 having an octagonal exterior wrenchengaging surface 18 at its center. The adapter 16 has a first smooth bore 20 which receives the end of the plastic pipe 10, the smooth bore 20 terminating at its outer end in a flared surface 22 so that the end of the pipe is slidably received in the smooth bore 20.

Disposed at the central region of the adapter 16 in the inner extremity of the first bore 20 is an inwardly extending shoulder 24 having a radial abutment wall 25 which limits the interior extent of movement of the pipe end 10. Alternatively, the palstic pipe may abut the exterior end of joint 14, and joined thereto by a fushion bond instead of being slipped into the bore 20. In this event, of course, the wall 25 flares outward, in a smooth curve. The shoulder 24 is preferably of the same interior diameter as the interior diameter of the pipe 10. The opposite radial abutment wall 26 merges with a second bore 28 which is threaded along its inner extent 30. This threaded portion 31) then merges with first, second, and third counterbored portions 32, 34, and 36, respectively, there being provided radial shoulders 38 and 40 between the first and second counterbored portions 32 and 34 and between the second and third counterbored portions 34 and 36, respectively.

A metal coupler 42 of generally cylindrical construction has an exteriorly threaded portion 44 of reduced diameter which is adapted to be threaded into the portion 30 of the second bore 28. This threaded portion 44 terminates at its intermediate end with an outwardly inclined surface 46, then with a short, fiat longitudinally extending surface 48 (FIGURE 3), the surfaces 46 and 48 being disposed in spaced apart relationship to the second counterbored portion 34 of the plastic adapter 16 to thereby define an annular space 50 therebetween when the joint is made up. The longitudinally flat surface 48 terminates with a radial shoulder 52 adapted to abut the radial shoulder 40 in the plastic adapter so that the exterior cylindrical surface 54 adjacent this radial shoulder 52 is nested within the third counterbored portion 36 of the adapter 16. The opposite outer end 56 of the metal coupler of reduced exterior diameter 42 is suitably bevelled and joined to the metal pipe end 12 by Welding. A resilient sealing gasket, such as an O-ring 58, is received in the annular space 50 between the metal coupler 42 and the plastic adapter 16.

In order to assemble the transition joint in FIGURES 13, the metal coupler 42 is welded to the metal pipe 12 and the O-ring 58 is slipped in the adapter 16 adjacent the second counterbored portion 34. The adapter 16 is then threaded onto the exteriorly threaded portion 44 of the metal coupler 42 so that when the joint between these elements is made up, the O-ring is radially compressed according to the radial distance between the surface of the second counterbore portion 34 and the surface 48. The coupler 42 is nested within the third counterbored portion 46 of the adapter 16. This latter arrangement acts as an effective stop shoulder.

The joint between these elements is thereby effected without straining the threaded connection between the elements and the Oring 58 provides a notably efficient seal Without undue stress on the elements. Thus the joint is tight but not so tight as to damage the threads and there is no sacrifice of an eflicient seal, the radial compression of the O-ring advantageously providing the desired pressure tight joint. Moreover, the O-ring 58 Will be compressed only within the prescribed limits and the compressive stress on the O-ring is not governed by the degree of tightness of the threaded joint between the coupler 42 and the adapter 16. In this regard the plastic pipe end 10 is simply inserted in the first bore 20 of the plastic adapter 16 and solvent welded in place by well-known techniques.

Numerous plastic materials are advantageously utilized in the construction of the adapter 16 and the plastic pipe end 10 including high molecular weight polymers and copolymers such as polyvinyl chloride, polyacrylonitrile, polybutadiene, nylon, polystyrene, polyethylene and polyvinylidine chloride, acetal and polypropylene materials, preferably moldable thermoplastic linear high molecular polymers of ethylinically unsaturated monomers.

The joint is quickly and easily assembled in the field by unskilled workmen and a notably reliable seal is formed therein.

FIGURES 4-6 show a modified embodiment of the joint in FIGURES 13 wherein the metal pipe 12 carries a metal coupler 60 with female threads Whereas the FIG- URE 1 coupler 42 carries male threads. In FIGURE 4, the coupler has a central bore 62.

The metal coupler 60 has a radially inwardly extending shoulder 66,- then merging with first, second, and third counterbored portions 68, 70 and 72. This arrangement of counterbored portions includes radial walls 74 and 76 between the first and second counterbored portions 68 and 70, and the second and third counterbored portions 70 and 72, respectively. The adapter 60 is interiorly threaded at 78, adjacent the outer portion of this third counterbored portion 72.

Carriedwithin the metal coupler 60 is an adapter 80 of generally cylindrical construction. This adapter 80 includes a minor diameter portion 82 adapted to be received within the first counterbored portion 68 of the metal coupler 60, terminating at its rearward end with a shoulder having a radial wall 84, this latter radial wall adapted to abut against the radial wall 76 and constituting a stop shoulder arrangement. The adapter 80 also includes a major diameter portion 86, exteriorally threaded at 88 for engagement with the threads 78 of the metal coupler 60. The interior surface 90 of the major diameter portion 86 is outwardly flared and is adapted to receive the plastic pipe end 10, the end surface of which abuts the radial wall 94 opposite the radial wall 84 of the shoulder.

Conveniently, the minor diameter portion 82 has an interior hexagonal shape 92 so that the adapter 80 may be rotated by a cooperatively shaped tool into threaded engagement with the coupler 60 after the coupler 60 is welded to the steel pipe 12. Longitudinal slots extending inwardly of the opposite end of the adapter 80 may perform this same function.

In this embodiment of the invention, an annular space is defined by the radial wall 74 and the second counterbored portion 70 of the metal coupler 60, the opposite radial shoulder 84 and exterior surface of the minor diameter portion 82 of the plastic adapter 80. This space receives an O-ring 96 which is adapted to seal the ele ments together When the adapter 80 is friction-Welded to the plastic pipe end 10. In this embodiment of the invention, the compression of the O-ring is limited by the spaced distance between the radial walls 74 and 84 when the wall 84 of the adapter 80 abuts the radial wall 76 of the metal coupler 60. Thus, the degree of tightness of the threads donot control the effectiveness of the seal but the seal is formed when the plastic adapter 80 abuts against the radialwall 76 of the metal coupler.

It will be appreciated that while this invention dis-. closes a joint which is connected to the end of a steel pipe 12, elements 12, 44 may form a lateral outlet of a T or other. such pipe fitting which is well-known in the art. Accordingly, the phrase metal pipe is used in a liberal sense to embrace such pipe fittings which lend themselves to the spirit of the instant invention.

From the foregoing description of the various embodiments of this invention, it is evident that the objects of this invention, together with many practical advantages joined to the metal pipe and an enlarged portion, said I enlarged portion including first, second and third cylindrical counterbored portions and first and second radial walls between the first and second counterbored portions and the second and third counterbore portions respec tively, the last-mentioned radial wall constituting a stop shoulder, and interior threads along said third counterbored portion; a plastic adapter of generally cylindrical construction and including a minor diameter portion having an axial extent greater than the axial extent of said second counterbored portion but less than the combined axial extent of said first and second counterbored portions adapted to be received and nest within said first counterbored portion, an outwardly extending radial wall merging with a major diameter portion, said radial wall adapted to engage said stop shoulder, said major diameter portion being exteriorly threaded for engagement with the interior threads of said metal coupler, the interior surface of said minor diameter portion 'being of generally hexagonal shape, an outwardly facing radial Wall merging with said enlarged diameter portion and constructed and arranged to limit the inward movementof said plastic pipe within-said plastic adapter, the innerv surface of said major diameter being outwardly flared;

said first radial wall and second counterbored portion of said metal coupler defining with the opposite radial wall of said adapter and theminor diameter portion an annular space, and a resilient sealing ring adapted to be carried within said annular space and compressed axially between said first radial wall and said opposite radial wall of said adapter to form a seal between said adapter and said coupler.

References Cited UNITED STATES PATENTS 2,638,243 5/ 1953 Davies.

2,776,151 1/ 1957 Harkenrider 285-423 X 2,866,473 12/1958 Schutter 285 -39 X 2,933,428 4/ 1960 Mueller 285-423 X 3,092,404 6/ 1963 MacWilliam 285-356 X 3,116,944 1/1964 Parker 285-332.2

FOREIGN PATENTS 897,257 5/ 1962 Great Britain.

CARL W. TOMLIN, Primary Examiner.

THOMAS F. CALLAGHAN, Examiner. 

